Amylase is one type of digestive enzyme. This enzyme hydrolyzes a glycoside bond, so as to digest amylose or amylopectin existing in starch to glucose, maltose, and an oligosaccharide. As such amylase, α-amylase (EC 3.2.1.1), β-amylase (EC 3.2.1.2), and glucoamylase (EC 3.2.1.3) have been known. The α-amylase irregularly cleaves the 1,4-α-bond of starch or glycogen to generate a polysaccharide or an oligosaccharide. The β-amylase decomposes starch or glycogen from the nonreducing terminus of a sugar chain to generate maltose. The glucoamylase decomposes the 1,4-α-bond of the nonreducing terminus of a sugar chain to generate glucose.
As an example of an amylase-measuring method, JP Patent Publication (Kokoku) No. 62-51960 B (1987) describes a method for measuring human α-amylase in a solution using an amylase substrate whose nonreducing terminus has been blocked. In addition, JP Patent Publication Kokoku) No. 2-36238 B (1990) describes an amylase-measuring method using a substrate whose nonreducing terminus is not protected and whose reducing terminus is a carboxylphenyl group. Moreover JP Patent Publication (Kokoku) No. 5-50274 B (1993) describes a method for measuring human α-amylase using a dry analysis element comprising a substrate whose nonreducing terminus is not protected. Furthermore, JP Patent Publication (Kokai) No. 2003-210195 A describes that when α-amylase activity is measured using an α-amylase activity-measuring solution comprising a predetermined concentration of NaCl and a predetermined concentration of CaCl2, the activity of wheat α-amylase whose optimal pH is on the acidic side can be measured with high sensitivity.